The AR-15 was a good choice. It is one of the most popular civilian firearms in the US, and as Gun Geeks will tell you, it’s the general purpose PC of firearms. It is very modular, with the ability to change stocks and uppers easily. It also has a large market of add on accessories, including pink plastic parts for the female (or male who just likes pink) shooters.

The inter-changeable upper (which includes the barrel) is key. You can convert your .223 AR-15 to 5.55mm NATO, .308 Winchester, .22 LR or even .50 Beowulf. All the same firearm by current US regulations.

On the lower end of the 3D printing scale, is the EDoodler. A hand held devices that extrudes a steam of heated material that you can create whole pieces or parts of a larger object. This is another Kickstarter project which blew past its original goal of $30,000 pretty fast. They have pledges of over $2 million and still have three weeks to go for fundraising.

Going even lower end, you have InstaMorph. I know people who swear by this stuff for really Q&D projects. You heat the stuff up and then are able to mold it. When it cools, it hardens. Kinda like a gateway drug for 3D printing.